1. Technical Field
Various embodiments of the present disclosure relate to high voltage integrated devices and, more particularly, to high voltage integrated devices having an improved on-resistance value and an improved breakdown voltage.
2. Related Art
Integrated devices having functions of both a controller and a driver are referred to as smart power devices. In general, output circuits of the smart power devices may be designed to include high voltage integrated devices such as lateral double diffused MOS (LDMOS) transistors operating at high voltages. In the high voltage integrated devices, breakdown voltages of the LDMOS transistors, for example, a drain junction breakdown voltage and a gate dielectric breakdown voltage are important factors that directly influence the stable operation of the LDMOS transistors. In addition, an on-resistance (Ron) value of the LDMOS transistors is also an important factor that influences electrical characteristics of the LDMOS transistors, for example, a current drivability of the LDMOS transistors.
In order to improve the drain junction breakdown voltage of the LDMOS transistors, a doping concentration of a drift region between a drain region and a channel region has to be reduced or a drift length of carriers in the drift region corresponding to a length of a current path in the drift region has to be increased. However, in such a case, the current drivability of the LDMOS transistors may be degraded and the on-resistance (Ron) of the LDMOS transistors increases.
On the contrary, if the doping concentration of the drift region between the drain region and the channel region increases or the drift length in the drift region decreases, the on-resistance (Ron) of the LDMOS transistors may be reduced and the current drivability of the LDMOS transistors may improve. However, the drain junction breakdown voltages of the LDMOS transistors may be lowered. That is, in the LDMOS transistors, the on-resistance and the drain junction breakdown voltage may be in a trade-off relationship.